People couldn't get enough of math questions this year as they debated the answers in Twitter threads and parenting forums. But they also lamented how much the complicated problems made their brains hurt.

This Chinese math question for fifth graders stumped adults.

The problem translates to: "If a ship had 26 sheep and 10 goats onboard, how old is the ship's captain?"

How is the amount of cargo a ship contains supposed to help you figure out how old the captain is?

The internet had a lot to say about this seemingly impossible math question, which became a trending topic on Twitter.

After the test question went viral, the Shunqing Education Department released a statement saying that the question was meant to gauge "critical awareness and an ability to think independently," according to a BBC translation.

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This second grade math problem left the internet seriously confused.

Second graders should be able to solve this.
INSIDER

The question is: "There are 49 dogs signed up to compete in the dog show. There are 36 more small dogs than large dogs signed up to compete. How many small dogs are signed up to compete?"

Popular reasoning was that if there are 49 dogs total, and there are 36 more small dogs than large dogs, you'd subtract 36 from 49. By that measure, there are 13 large dogs and 36 small dogs, meaning the answer is 36. But seeing as that would mean there are 23 more small dogs than large dogs, that isn't right.

The teacher who gave the question later told Popsugar, "The district worded it wrong." But as it stands, the answer is 42.5: 49 - 36 = 13, 13 / 2 = 6.5, and 36 + 6.5 = 42.5. Apparently, half of a dog competed at the dog show.

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People couldn't agree on the answer to a question about buying and selling horses.

Here's the question: "A man buys a horse for $60. He sells the horse for $70. He then buys the horse back for $80. And he sells the horse again for $90. In the end, how much money did the man make or lose? Or did he break even?"

Answers in the Mumsnet thread ranged from making $10, $20, and $30 to breaking even. So what's the solution?

What seems to be throwing people off is the fact that the man sells the horse for $70 and then buys it back for $80, making it look like he spent $10 more. But the correct way to solve the problem is to think of the two transactions as separate: -60 + 70 = 10 and -80 + 90 = 10.

The man makes $10 with each sale, therefore he earns a total of $20.

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Author Ed Southall shared a math problem on Twitter that some people managed to get right.

Ed Southall, author of "Geometry Snacks," shared a photo of a pink triangle inside a square and challenged people to figure out how much of the square is shaded pink. Some Twitter users gave up immediately, but others rose to the challenge.

According to Business Insider's quant reporter, Andy Kiersz, the key to solving the problem is the height of the pink triangle.

The area of a triangle is 1/2 (base x height). If we assume that the square is a 1 x 1 unit, we can see that the base of the pink triangle is 1, the length of the square. All we need to figure out is the height.

"The key trick is that the little triangle up top is similar to the pink triangle, which means that the little triangle is just a smaller version of the pink triangle," Kiersz said.

"A property of similar triangles is that the ratio of the triangles' heights will be the same as the ratio of their bases," he said. "Since the pink triangle's base is twice the little triangle's base, its height is also twice the little triangle's height. But we know that the little triangle's height plus the pink triangle's height is 1, so that means the pink triangle's height is 2/3. Plug that on in and we get our area = 1/2 x base x height = 1/2 x 1 x 2/3 = 1/3."

According to Talwalkar, the easiest way to answer the first question about when the lights will all be off is to map out the intervals for each lighthouse and see where their "off" sections overlap. The answer: after five seconds, when the third light has just turned off and the first and second lights are still off.

To determine when all of the lights will come on together, you need to find the smallest common multiple of the intervals when the lights will be on. The answer to that question is that the lighthouses will all come on together at 120 seconds, or two minutes.

The brainteaser consists of four math equations, each of which adds to or multiplies a numerical sum or product. In place of variables like x or y, however, the brainteaser substitutes ice cream cones that are either empty or have scoops of white ice cream, pink ice cream, or both.

To solve the puzzle, you have to figure out what number the empty ice cream cones, white ice cream scoops, and pink ice cream scoops each represent.

The answer is that the empty ice cream cone represents the number three, the white ice cream scoop represents the number two, and the pink ice cream scoop represents the number one.

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A Quora thread of difficult SAT math questions included one people called the "meanest test problem ever."

There are a few ways to solve it, but Talwalkar presented a simple shortcut.

The first class had an average of 70. That's 16 points below the average score of 86. In other words, 86 - 70 = 16. Since there are p students in the class, the difference from the average is 16 p.

The second class had an average of 92. That's 6 points more than the average of 86. In other words, 92 - 86 = 6. There are n students in this class, so the difference from the average is 6 n.

Because these classes average out together — as the problem says, "when the scores of the two classes are combined" — the deficit of points has to be equal to the surplus of points. Therefore, 16 p is equal to 6 n.

Turning that into an equation, we can easily figure out what p/n is:

16 p = 6 n

p/n = 6/16, or 3/8.

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A British mathematician says he solved the "single most important open problem" in math after 160 years, but it still needs to be peer reviewed.

The $1 million prize goes to whoever can prove that the equation applies to all prime numbers. British mathematician Sir Michael Atiyah said he solved the 160-year-old problem, but his solution needs to be peer reviewed before he can take home the prize money.

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This brainteaser has a missing number.

What is the missing number?
Courtesy of Puzzles9

Similar to Sudoku, this puzzle created by Puzzles9 consists of a rectangle with nine squares, each containing a number, except for the bottom-right square.

Read the first two rows of numbers horizontally, each as one number — 289 and 324.

The pattern is that 17 x 17 = 289 and 18 x 18 = 324. So it stands to reason that the bottom row will be 19 x 19 = 361. Therefore, the missing number is one.

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This brainteaser features three pentagons, each with a set of five numbers.

From left to right, let's label the pentagons A, B, and C. The difference between the numbers in pentagons A and B can be found in Pentagon C in the same location across the board. In other words, Pentagon B - Pentagon A = Pentagon C.